The IEEE 802.11s standardization committee group is currently working on an extension of the 802.11 standard for such type of networks. The current IEEE 802.11s standard specification, version D1.03, incorporated herein by reference, defines an IEEE 802.11 Wireless LAN (WLAN) Mesh using the IEEE 802.11 MAC/PHY layers that supports both individually addressed and group addressed delivery over self-configuring multi-hop topologies. Mesh networks according to the 802.11s standard, or so-called meshes, operate as wireless co-operative communication infrastructures between numerous individual wireless transceivers. A mesh may be centralized or decentralized. Stations or mesh nodes (MP) in the mesh communicate with their neighboring adjacent nodes only and thus act as repeaters to transmit message data from nearby nodes to peers that are too far to reach. Terminology specific to the 802.11s standard will be used in the following paragraphs to illustrate the invention and whenever applicable, the terms used should be understood as defined in the 802.11s standard.
By definition, in a network based on the 802.11s standard mesh points MPs communicate over a mesh. A mesh includes two or more mesh points. A mesh point MP is an IEEE 802.11 entity that contains an IEEE 802.11-conformant medium access control and physical layer interface to the wireless medium that supports mesh services as defined in the 802.11s standard.
Mesh points are synchronized when they have established a common time reference thereby enabling efficient reservation of the wireless medium for data transfer, beaconing and advanced power save modes. The current 802.11s specification defines a protocol for synchronization if mesh points desire to synchronize with one another. Synchronization is not mandatory over a mesh however, when feasible, it greatly improves communication between mesh points. 802.11s D1.03 defines a synchronization capability field (see 802.11s D1.03 7.3.2.53.5 Synchronization Capability field) with 3 sub-fields: a Supporting Synchronization sub-field, a Synchronizing with peer MP subfield and a Synchronizing with peer MP subfield. The Supporting Synchronization sub-field is set to 1 if the MP supports timing synchronization with peer MPs and 0 otherwise. The Requests Synchronization from Peer subfield is set to 1 if the MP requests MP peers attempting to communicate with it to synchronize with it and 0 otherwise. The Synchronizing with peer MP subfield set to 1 if the non-access point MP is currently a synchronizing MP and 0 otherwise. The synchronization capability field is contained in a mesh capability element as explained in 802.11s 7.3.2.53 to advertise mesh services. It is contained in Beacon frames transmitted by MPs and is also contained in probe request/response messages and (re)association request/response messages. In the current synchronization procedure, synchronization is treated as a mesh-wide property and the parameters for this mesh wide property are established by the MP that initiates the mesh, see Section 11A10.3.2.
However, this procedure has various disadvantages. Firstly, it can happen that the MP that establishes the mesh does not initiate synchronization, and this could then never be changed, and the mesh could not develop into a synchronized mesh. Secondly, the procedure is unclear as to what happens when two or more MPs simultaneously start a mesh. Thirdly, the procedure is unclear as to what happens if two synchronized meshes need to be merged.